The dripless means for a fuel dispensing nozzle relates to nozzles used to dispense gasoline into automobile fuel tanks, in general, and more specifically to improvements in the spout, the vent tube and the bushing to reduce the number of drips from the spout after fueling. Unique aspects of the present dripless means are grooves applied to the interior surface of the spout, a bushing with arc weirs, and a restrictor in the vent tube.
As is well known in the art, and to the public, gasoline-dispensing nozzles of the type used in most service stations have a spout which is inserted into the inlet of the filler pipe of an automobile fuel tank. The diameter of the spout is less than that of the filler pipe resulting in a gap between the side of the spout and the filler pipe. Consequently, gasoline vapors leaked into the atmosphere. Escaping gasoline vapors raise pollution concerns and have triggered government regulations of fuel dispensing nozzles. Regulations require such nozzles to reduce the pollutants released to the atmosphere. A flexible bellows assembly fitted over the spout is one way of meeting the regulations, usually called the balanced pressure nozzle.
However, the regulations further address drops of fuel that exit the spout after fueling. A user releases a lever to stop fuel flow into the nozzle. Some fuel remains within the nozzle and the spout. Under gravity, the fuel exits the spout as drops and evaporates. The California Air Resources Board is strict to the extent that it limits nozzles to no more than three drops emitted from a spout after fueling. A further test by the Board requires draining of the spout within ten seconds when oriented at a thirty degree angle in the vehicle fill opening, commonly called the Post Fueling Drip Test.
Prior art designs provided valves at the end of the spout to block drops. Though stopping the fuel drops, such valves added to the weight and cost of a nozzle. These prior art valves tended to corrode and to malfunction after substantial usage. Along with wearing of valves, tipping of nozzles to the side may release upwards of six drops of fuel from the spout.
The present invention overcomes the limitations of the prior art. That is, in the art of the present invention, a dripless means, prevents the fuel dripping from the spout without a valve.
The difficulty in providing a dripless means is shown by the operation of a typical nozzle. A user completes fueling and releases a lever on a nozzle. The nozzle retains some fuel in the spout and internal parts of the nozzle, such fuel that has not dispensed into an automobile's fuel tank. As the user replaces the nozzle at the pump, fuel follows gravity towards the distal end of the spout. The fuel encounters a valve that closes automatically upon release of the lever. Fuel becomes drops beyond the valve. As the valve wears, more fuel escapes and generates drops.
The use of nozzles to dispense fuel is known in the prior art. For example, the U.S. Pat. No. 5,127,451 to Fink and Mitchell discloses a fuel dispensing nozzle improvement of a bellows to trap fuel vapors during filling of a tank. The bellows surrounds the spout for its full length and captures vapors. However, upon nozzle shutoff, such fuel remains in the spout by capillary action or otherwise. The undisclosed surface of the spout permits fuel to exit the spout as drops. Thus, the prior art type of devices do not provide for reducing the number of fuel drops leaving a nozzle.